﻿<html>
<head>  
   <meta charset="utf-8">
   <title>123</title>
     <style type="text/css">
       .top {
            hheight:54px;
            width:100%;
            position:absolute:
            top:0;
            left:0;
            background:ragb(255,0,0,0.5);
          }
  </style>
</head>
<body>
<p>置于透明层下面的文字</p>
<div class="top"></div>
</body>
</html>